<?php
/**
 * Class definition for ReCaptcha
 * @package		core
 */

/**
 * This is a PHP library that handles calling reCAPTCHA.
 *    - Documentation and latest version
 *          http://recaptcha.net/plugins/php/
 *    - Get a reCAPTCHA API Key
 *          http://recaptcha.net/api/getkey
 *    - Discussion group
 *          http://groups.google.com/group/recaptcha
 *
 * @copyright Copyright (c) 2007 reCAPTCHA -- http://recaptcha.net
 * @author Mike Crawford
 * @author Ben Maurer
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */

/**
 * The reCAPTCHA server URL's
 */
define("RECAPTCHA_API_SERVER", "http://api.recaptcha.net");
define("RECAPTCHA_API_SECURE_SERVER", "https://api-secure.recaptcha.net");
define("RECAPTCHA_VERIFY_SERVER", "api-verify.recaptcha.net");

/**
 * @package		core
 * @subpackage	utils
 */
class ReCaptcha {
	/**
	 * Encodes the given data into a query string format
	 * @param array $data An rray of string elements to be encoded.
	 * @return string  encoded request
	 */
	public static function _recaptcha_qsencode($data) {
		$req = "";
		foreach ($data as $key => $value)
			$req .= $key . '=' . urlencode(stripslashes($value)) . '&';

		// Cut the last '&'
		$req = substr($req, 0, strlen($req) - 1);
		return $req;
	}

	/**
	 * Submits an HTTP POST to a reCAPTCHA server
	 * @param string $host
	 * @param string $path
	 * @param array $data
	 * @param int $port
	 * @return array response
	 */
	public static function _recaptcha_http_post($host, $path, $data, $port = 80) {

		$req = self :: _recaptcha_qsencode($data);

		$http_request = "POST $path HTTP/1.0\r\n";
		$http_request .= "Host: $host\r\n";
		$http_request .= "Content-Type: application/x-www-form-urlencoded;\r\n";
		$http_request .= "Content-Length: " . strlen($req) . "\r\n";
		$http_request .= "User-Agent: reCAPTCHA/PHP\r\n";
		$http_request .= "\r\n";
		$http_request .= $req;

		$response = '';
		if (false == ($fs = @ fsockopen($host, $port, $errno, $errstr, 10))) {
			die('Could not open socket');
		}

		fwrite($fs, $http_request);

		while (!feof($fs))
			$response .= fgets($fs, 1160); // One TCP-IP packet
		fclose($fs);
		$response = explode("\r\n\r\n", $response, 2);

		return $response;
	}

	/**
	 * Gets the challenge HTML (javascript and non-javascript version).
	 * This is called from the browser, and the resulting reCAPTCHA HTML widget
	 * is embedded within the HTML form it was called from.
	 * @param string $pubkey A public key for reCAPTCHA
	 * @param string $error The error given by reCAPTCHA (optional, default is null)
	 * @param boolean $use_ssl Should the request be made over ssl? (optional, default is false)

	 * @return string The HTML to be embedded in the user's form.
	 */
	public static function recaptcha_get_html($pubkey, $error = null, $use_ssl = false) {
		if ($pubkey == null || $pubkey == '') {
			die("To use reCAPTCHA you must get an API key from <a href='http://recaptcha.net/api/getkey'>http://recaptcha.net/api/getkey</a>");
		}

		if ($use_ssl) {
			$server = RECAPTCHA_API_SECURE_SERVER;
		} else {
			$server = RECAPTCHA_API_SERVER;
		}

		$errorpart = "";
		if ($error) {
			$errorpart = "&amp;error=" . $error;
		}
		return '<script type="text/javascript" src="' . $server . '/challenge?k=' . $pubkey . $errorpart . '"></script>

					<noscript>
				  		<iframe src="' . $server . '/noscript?k=' . $pubkey . $errorpart . '" height="300" width="500" frameborder="0"></iframe><br/>
				  		<textarea name="recaptcha_challenge_field" rows="3" cols="40"></textarea>
				  		<input type="hidden" name="recaptcha_response_field" value="manual_challenge"/>
					</noscript>';
	}

	/**
	  * Calls an HTTP POST function to verify if the user's guess was correct
	  * @param string $privkey
	  * @param string $remoteip
	  * @param string $challenge
	  * @param string $response
	  * @param array $extra_params an array of extra variables to post to the server
	  * @return ReCaptchaResponse
	  */
	public static function recaptcha_check_answer($privkey, $remoteip, $challenge, $response, $extra_params = array ()) {
		if ($privkey == null || $privkey == '') {
			die("To use reCAPTCHA you must get an API key from <a href='http://recaptcha.net/api/getkey'>http://recaptcha.net/api/getkey</a>");
		}

		if ($remoteip == null || $remoteip == '') {
			die("For security reasons, you must pass the remote ip to reCAPTCHA");
		}

		//discard spam submissions
		if ($challenge == null || strlen($challenge) == 0 || $response == null || strlen($response) == 0) {
			$recaptcha_response = new ReCaptchaResponse();
			$recaptcha_response->is_valid = false;
			$recaptcha_response->error = 'incorrect-captcha-sol';
			return $recaptcha_response;
		}

		$response = self :: _recaptcha_http_post(RECAPTCHA_VERIFY_SERVER, "/verify", array (
			'privatekey' => $privkey,
			'remoteip' => $remoteip,
			'challenge' => $challenge,
			'response' => $response
		) + $extra_params);

		$answers = explode("\n", $response[1]);
		$recaptcha_response = new ReCaptchaResponse();

		if (trim($answers[0]) == 'true') {
			$recaptcha_response->is_valid = true;
		} else {
			$recaptcha_response->is_valid = false;
			$recaptcha_response->error = $answers[1];
		}
		return $recaptcha_response;

	}

	/**
	 * gets a URL where the user can sign up for reCAPTCHA. If your application
	 * has a configuration page where you enter a key, you should provide a link
	 * using this function.
	 * @param string $domain The domain where the page is hosted
	 * @param string $appname The name of your application
	 */
	public static function recaptcha_get_signup_url($domain = null, $appname = null) {
		return "http://recaptcha.net/api/getkey?" . self :: _recaptcha_qsencode(array (
			'domain' => $domain,
			'app' => $appname
		));
	}

	public static function _recaptcha_aes_pad($val) {
		$block_size = 16;
		$numpad = $block_size - (strlen($val) % $block_size);
		return str_pad($val, strlen($val) + $numpad, chr($numpad));
	}

	/* Mailhide related code */

	public static function _recaptcha_aes_encrypt($val, $ky) {
		if (!function_exists("mcrypt_encrypt")) {
			die("To use reCAPTCHA Mailhide, you need to have the mcrypt php module installed.");
		}
		$mode = MCRYPT_MODE_CBC;
		$enc = MCRYPT_RIJNDAEL_128;
		$val = self :: _recaptcha_aes_pad($val);
		return mcrypt_encrypt($enc, $ky, $val, $mode, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
	}

	public static function _recaptcha_mailhide_urlbase64($x) {
		return strtr(base64_encode($x), '+/', '-_');
	}

	/* gets the reCAPTCHA Mailhide url for a given email, public key and private key */
	public static function recaptcha_mailhide_url($pubkey, $privkey, $email) {
		if ($pubkey == '' || $pubkey == null || $privkey == "" || $privkey == null) {
			die("To use reCAPTCHA Mailhide, you have to sign up for a public and private key, " .
			"you can do so at <a href='http://mailhide.recaptcha.net/apikey'>http://mailhide.recaptcha.net/apikey</a>");
		}

		$ky = pack('H*', $privkey);
		$cryptmail = self :: _recaptcha_aes_encrypt($email, $ky);

		return "http://mailhide.recaptcha.net/d?k=" . $pubkey . "&c=" . self :: _recaptcha_mailhide_urlbase64($cryptmail);
	}

	/**
	 * gets the parts of the email to expose to the user.
	 * eg, given johndoe@example,com return ["john", "example.com"].
	 * the email is then displayed as john...@example.com
	 */
	public static function _recaptcha_mailhide_email_parts($email) {
		$arr = preg_split("/@/", $email);

		if (strlen($arr[0]) <= 4) {
			$arr[0] = substr($arr[0], 0, 1);
		} else
			if (strlen($arr[0]) <= 6) {
				$arr[0] = substr($arr[0], 0, 3);
			} else {
				$arr[0] = substr($arr[0], 0, 4);
			}
		return $arr;
	}

	/**
	 * Gets html to display an email address given a public an private key.
	 * to get a key, go to:
	 *
	 * http://mailhide.recaptcha.net/apikey
	 */
	public static function recaptcha_mailhide_html($pubkey, $privkey, $email) {
		$emailparts = self :: _recaptcha_mailhide_email_parts($email);
		$url = self :: recaptcha_mailhide_url($pubkey, $privkey, $email);

		return htmlentities($emailparts[0]) . "<a href='" . htmlentities($url) .
		"' onclick=\"window.open('" . htmlentities($url) . "', '', 'toolbar=0,scrollbars=0,location=0,statusbar=0,menubar=0,resizable=0,width=500,height=300'); return false;\" title=\"Reveal this e-mail address\">...</a>@" . htmlentities($emailparts[1]);

	}

}
?>
